> For the complete documentation index, see [llms.txt](https://docs.rigoblock.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rigoblock.com/solidity-api-reference/protocol/core/sys.md).

# Sys

- [MixinAbstract](https://docs.rigoblock.com/solidity-api-reference/protocol/core/sys/mixinabstract.md)
- [MixinFallback](https://docs.rigoblock.com/solidity-api-reference/protocol/core/sys/mixinfallback.md)
- [MixinInitializer](https://docs.rigoblock.com/solidity-api-reference/protocol/core/sys/mixininitializer.md)